Meso-scale hydrological modeling in the boreal forest/discontinuous permafrost ecosystem is very difficult due to the inadequate representation of important small-scale landscape features that are difficult to derive from large-scale data products. Permafrost and vegetation cover are among these small-scale features that mainly control the hydrology and ecosystem composition of the basins. Due to the presence or absence and spatial distribution of permafrost, watersheds in this region host sharply contrasting ecosystems which vary over short horizontal spatial scales. The distribution of permafrost is also controlled by climatic, geologic, topographic factors. However, topography is the primary contro that modifies the local climate through its effect on direct solar radiation. In general, north-facing slopes and valley bottoms are underlain with permafrost while south-facing slopes are generally permafrost free. To accurately simulate the hydrology of the region at any desired spatial and temporal scale, it is necessary to implement these generalized relationships among permafrost, vegetation and topography into process-based distributed hydrological models.
The objective of this study is to improve the parameterization of mesoscale hydrological modeling through fine-scale observation and modeling. Aspect, derived from 30m Digital Elevation Model (DEM), is used as a proxy for permafrost distribution and vegetation composition parameterization. Small-scale parameterizations were conducted at the two contrasting sub-basins of the Caribou-Poker Creeks Research Watershed (CPCRW) using the Variable Infiltration Capacity (VIC) mesoscale hydrological model. The small-scale parameterization study in the CPCRW improves stream flow simulation in both permafrost dominated (5.7 km2) and permafrost-free (5.2 km2) sub-watersheds. In order to test the extent to which these small-scale parameterizations are valid at large scale, stream flow was simulated at the Chena River Basin (area ~5,478 km2), located in Interior Alaska, using the small-scale parameterizations results of CPCRW. Both results suggest that aspect based parameterization of the mesoscale hydrological modeling in the region improve prediction of stream flow.
In this seminar, I will present the small-scale vegetation cover and soil property parameterization and streamflow simulations for the CPCRW and Chena River basins.